It seems I need to learn a 1) lot about syntax, coming from daily PHP and bash use, and 2) maybe play around with this OnChange event handler next; it seems promising.
Playing around with code is the best way to learn. There are also lots of tutorials in the
wiki and you may find some recomendations for outside ones by looking for "Turorial" in this forum. Whihc leads us to ...
I see a lot of Delphi results when I search for examples of the various handlers and objects in use; can I expect that code to be portable to my FP project?
In genreal yes; FP (and Lazarus) try to be as compatible as possible with Borland's Delphi. Although there are some differences there are (usually) not unsurmountable obstacles and one can easily work around the few you may find.
And as a last resource, if you find yourself down a deep pit from where you don't know how to escape, there's always this forum. Someone, somewhere, will probably know where the exit lies and won't mind sharing the trick.
Have luck!